ZHA: why do i use CustomeDevice quirk?

My Ikea Styrbar Remote control N2 signature has not ‘groups’ cluster (0x0004) and comes as a customedevice. Why is that? i hope the absence of the groups cluster prevents binding to the group. How can i set ZHA quirk for this device?

{
  "node_descriptor": {
    "logical_type": 2,
    "complex_descriptor_available": 0,
    "user_descriptor_available": 0,
    "reserved": 0,
    "aps_flags": 0,
    "frequency_band": 8,
    "mac_capability_flags": 128,
    "manufacturer_code": 4476,
    "maximum_buffer_size": 82,
    "maximum_incoming_transfer_size": 82,
    "server_mask": 11264,
    "maximum_outgoing_transfer_size": 82,
    "descriptor_capability_field": 0
  },
  "endpoints": {
    "1": {
      "profile_id": "0x0104",
      "device_type": "0x0820",
      "input_clusters": [
        "0x0000",
        "0x0001",
        "0x0003",
        "0x0020",
        "0x1000",
        "0xfc57"
      ],
      "output_clusters": [
        "0x0003",
        "0x0005",
        "0x0006",
        "0x0008",
        "0x0019",
        "0x1000"
      ]
    }
  },
  "manufacturer": "IKEA of Sweden",
  "model": "Remote Control N2",
  "class": "zigpy.quirks.v2.CustomDeviceV2"
}

the CustomDeviceV2 seems ok. The device must be ‘reconfigured’ from the device card (Integration-ZHA-Remote Control)- keep pressed a button on the device. Binding to group does not work, bind to specific device (bulb) Discussion on github